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Re: indexes and database links

From: joseph Li <lijoecyn_at_netspace.net.au>
Date: 1998/03/29
Message-ID: <6fk4c8$9s9$1@otis.netspace.net.au>#1/1

In article <6f1ho4$7vt$1_at_netnews.upenn.edu>, yates_at_sas.upenn.edu (John H. Yates) says:
>
>FlyingVee (b-horton_at_worldnet.att.net) wrote:
>> John H. Yates wrote:
>> >
>> > Could the lack of response to this query mean that others don't have this
>> > problem?
>> >
>> > John H. Yates (yates_at_hiker.sas.upenn.edu) wrote:
>> > > Our Oracle server queries databases on another machine via a database link.
>> > > We have found that indexes on the remote server are not used for these
>> > > queries. How can we make our queries use the remote database indexes?
 

>> > > Thanks, John
>> > > yates_at_sas.upenn.edu
>> How do you know they aren't?.
>
>My staff has been told that by those who run Oracle on the machine we
>connect to. When they run our query, it takes less than a minute. When
>we run the query from our machine over the net, it takes more than five
>minutes. (for more details I'll have to ask my staff on Monday)
>
>John

Try setting SQL_TRACE to TRUE before running the query that access the remote Oracle7 database, that should tell you the execution plan ie. whether a full-table scan was performed remotely. As from my own experience I have performed joins between local and remote Oracle7 databases, the local O7 optimiser knew about the existence of the remote indexes. A different story when the remote database is non-Oracle say Rdb.

Joseph Received on Sun Mar 29 1998 - 00:00:00 CST

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